World Modelling
• Simple single-inheritance taxonomy of "kinds": direction, room, thing, container, supporter, person, man, woman, animal, door, vehicle, device
• New kinds easy to make
• Routes between rooms assumed two-way, but can be one-way, or asymmetric
• Automatic support for two-sided and one-sided doors
• Locks and keys
• Adjacency of rooms, and optimal routes through the map (with or without ability to use doors) easily calculated
• Holdall containers store away less-used possessions of the player
• Each person can have possessions and clothing, with rules governing which are visible and which concealed
• Carrying capacity monitored for all people and containers
• Backdrops are present in many rooms (for modelling the sky, for instance)
• Map can be divided up into “regions”, as required
• Fully supports "parts": any thing can have another thing joined to it as a part, and parts are detachable and reattachable during play, at the writer's discretion
• Automatic checking of whether any given person can see or touch any given thing, using fully modifiable rules
• Composite objects can be assembled throughout the model: for instance, we can specify that every person has a part called the "head", or that every door has a container part called the "letterbox"
• Duplicates are made as required: "Four gold coins are in the box"
Relations
• The meaning of verbs (such as "to contain") is defined in terms of relations between pairs (X is spatially inside Y)
• Create new verbs and new relations (for instance, we could define a suspicion relation as the meaning of a new verb "to suspect")
• Relations can be automatically reciprocal (e.g. for marriage) or not (e.g. for love)
• Relations can group things into mutually exclusive groups (e.g. grouping people by nationality)
• Alternatively, relations can be given explicit definitions in terms of the current situation ("Nearness relates a room (called A) to a room (called B) when the number of moves from B to A is less than 3.")
• Relations can also apply to values ("if 12 is divisible by 3") or between things and values ("if the box is made of wood")
Actions
• Over one hundred basic actions provide for a wide range of movement and contact during play
• New actions are easy to create
• Actions can be carried out by any character in the narrative, not only the player
• All restrictions on actions (such as being unable to take something in a sealed glass box) apply equally to all characters
• All outcomes of actions also apply equally
• "Persuasion rules" govern what happens when one character asks another to do something
• Every action results in success or failure: in the event of failure, the rule which caused the failure can be found out
• Actions "out of world" handle game control commands, such as saving, which do not happen in the model world
• Names can be given which characterise certain actions ("Attacking a person is violent behaviour")
Rules
• Rules govern every aspect of play, from how names are printed to when a closed box can be opened
• New rules can be applied to individual actions, or kinds of action ("After violent behaviour in the museum...")
• Rules can apply everywhere, or to individual items, or in individual places, or regions, or in the presence of given things, or in specific circumstances
• Special rules for "going" actions can apply to movement using certain vehicles, or through certain doors, or while pushing certain objects, or going from or to given places, or going nowhere (because the map provides no such route)
• Rules can apply to repeated actions ("Instead of going nowhere for the 20th time...", "After waiting for four to six turns...")
• Rules can apply at all times, or only during certain scenes
• New “rulebooks” of rules can be created to handle complex situations
• Procedural rules can alter the behaviour of other rules even during play
• There are no rules which cannot be changed
Chronology
• Time of day is maintained throughout play
• Times can be printed exactly or approximately (e.g., "to the nearest five minutes")
• Progress can be supervised with points and rankings
• Rules can be applied at specific moments ("At 4 PM: ...") or at relative times ("in four turns from now")
• Broad chronology is organised into scenes
• Scenes begin or end as when specified conditions are met, with suitable rules to set them up or dismantle them, like scenery changes in plays
• Scenes can lead automatically into other scenes
• Scenes can have multiple endings with different outcomes
• Scenes repeat as necessary
Features